What it is and how it works
Tumours need to grow new blood vessels in order to grow, and they do so by releasing a signal called VEGF. Bevacizumab is an antibody that traps that signal: it is an anti-angiogenic drug. It does not kill tumour cells directly; it "starves" them of blood supply and, in addition, normalises the existing vessels so that chemotherapy gets in better. That is why it is always given together with chemotherapy (FOLFOX, FOLFIRI, CAPOX, FOLFOXIRI) and never on its own as the main treatment.
Unlike the anti-EGFR antibodies (cetuximab, panitumumab), it works equally well with mutated or wild-type RAS and with right- or left-sided tumours. It is the usual first-line option when the tumour has a RAS or BRAF mutation, and also in second line (it can be continued when the chemotherapy is changed). In the maintenance phase, after the first months of intensive treatment, it is usually continued with capecitabine or 5-FU plus bevacizumab, with fewer side effects.
Biosimilars (equivalent versions of the same antibody under other brand names) have existed for years. They are just as effective and safe; being switched to another brand does not mean a worse treatment.
How it is given
Intravenously, on the same day as chemotherapy, every 2 weeks (with FOLFOX/FOLFIRI) or every 3 weeks (with CAPOX). The first infusion takes about 90 minutes; later ones are shortened to 30 minutes.
Side effects: what to watch
| Effect | How common | What to do |
|---|---|---|
| High blood pressure | Very common | Measure your blood pressure at home once or twice a week and write it down. If it goes above the level your team tells you (usually repeated readings over 140/90), let them know: it is controlled with tablets and rarely requires stopping treatment. |
| Protein in the urine | Common, no symptoms | Checked with a urine dipstick before each cycle. If it is high, the drug is paused until it falls. |
| Nosebleeds, bleeding gums | Common, mild | Usually stops with pressure alone. Report it if it lasts more than 10-15 minutes or is heavy. |
| Slow wound healing | Matters if there is surgery | It is stopped at least 6-8 weeks before a planned operation (including minor surgery and complex tooth extractions) and not restarted until 4-8 weeks after surgery, with the wound closed. |
| Headache, hoarseness, tiredness | Common, mild | Mention them at your appointment. |
Rare but serious effects
- Bowel perforation (1-2 %): higher risk if the primary tumour is still in the colon, there is bowel inflammation or recent surgery. Warning sign: sudden, severe abdominal pain, with or without fever or vomiting. This is an emergency.
- Arterial clots (heart attack, stroke) and venous clots: rare, more likely over 65 with a previous history. Chest pain, difficulty speaking or weakness on one side of the body, painful swelling of one leg: emergency department.
- Serious bleeding: very rare in colon cancer; closer monitoring if you take anticoagulants (not an absolute contraindication).
- Fistulas and hypertensive crisis: exceptional.
When it is avoided or delayed
- The 4 weeks after major surgery, or if a wound has not closed.
- Blood pressure that cannot be controlled with medication.
- A recent heart attack, stroke or major bleed.
- Untreated or bleeding brain metastases (treated ones are not an obstacle).
What to ask at your appointment
- Why bevacizumab rather than an anti-EGFR in my case? (RAS, BRAF, tumour side.)
- How often should I check my blood pressure at home, and above what reading should I call you?
- If I need an operation (or a tooth out), how far in advance does it have to be stopped?
- Will it be continued during maintenance or when the chemotherapy is changed?
- Which symptoms are emergencies with this drug?
